Composite oscillator for electromagnetic waves



Jan. 7, 1936. J. 5. STONE COMPOSITE OSCILLATOR FOR ELECTROMAGNETIC WAVESFiled June 1, 1933 INVENTOR film/n Sta/Le Stone ATTORNEY Jan. 7, 1936.J. 5. STONE 2,026,712

COMPOSITE OSCILLATOR FOR ELECTROMAGNETIC WAVES Filed June I, 1933 3Sheets-Sheet 2 INVENTOR Jlu a Stwwe Sta/Le ATTORNEY Jan. 7, 1936. I J.s. STONE 2;026,7l2'

COMPOSITE OSCILLATOR FOR ELECTROMAGNETIC WAVES Filed Ju ne l, 1933 3Sheets-Sheet 5 /=l (goproxmate) 76' z' /l watts 5 kg #93 5% 1/2 A zj/z21 54/2 5/1 7A/2 4A 7@.2 i /21 Quits 3% (2) (2) '2 2 A 52 2 22 52 2INVENTOR John Stane 660m BY 561M A'fTORNEY Patented Jan. 7, i936 I s l,i

UNITED STATES PATENT. OFFICE COMPOSITE OSCILLATOR FOR ELECTRO- MAGNETICWAVES John Stone Stone, San Diego. Calif., assignor to AmericanTelephone and Telegraph Company,

a corporation of New York Application June 1, 1933, Serial No. 673,926

4 Claims. (01. 250-33) An object of my invention is to provide a new '10is a corresponding diagram for electromotive and improved system forgenerating and radiatforces; in Fig. 11 the diagram of Fig. 7 has beening electromagnetic waves. Another object is extended to severaladjacent and consecutive to accomplish the radiation of such waveswithcomponent oscillators; in Fig. 12 the diagram of substantial energy.My invention may 'beprac- Fig. 8 has been similarly extended; Fig. 13 isa 5 ticed advantageously for the effective generation diagrammatic axialor longitudinal section of and radiation of waves of comparatively shortan oscillator built according to the principle of length. In one aspectthis invention involves my invention; Fig. 14 is a diagram illustratingproviding an effective radiating oscillator of a how the variouscomponent oscillators may be length considerably greater than a halfwave marked off from each other by impedance con- 10 length. Thisoscillator may comprise adjacent nections instead of by physicaldiscontinuities; oscillators lapping past each other and each Fig. 15.is a diagram in which the representation shorter than the overalllength of the composite is changed somewhat from that of Fig. 1; Figs.oscillator. The foregoing statement of objects 16 and 1''! are diagramsshowing radiated wave l5 and advantages of my invention has been madeshapes corresponding respectively to parts (I I) 15 with reference toradiation or transmission of and (1) of Fig. 3; Fig. 18 is a diagramshowing energy, but it is well known that in general any the power fromthe central part of a well-known good radiator of energy is an equallygood abtype of oscillator as a function of its length; and sorber ofenergy. Any system will have the same Fig. '19 is a similar diagram withcomparison of go absorption spectrum as its radiation spectrum. aradiator made according tomy invention. 20

Accordingly, it will be understood that structures An embodiment of myinvention is shown diato operate as composite radiators embodying mygrammatically in Fig. 1. Side by side are two present invention will bereadily applicable to rows of component oscillators, such as theosciloperate as receivers. For convenience I shall lator 2,5 in one rowor the oscillator 22 in the make the following description principallyfor other row. Each such oscillator consists of a 25 radiators. All theforegoing and other features, length of straight conductor with a coil23 inobjects and advantages of my invention will beterposed at itsmiddle, and each oscillator in one come apparent in connection with thefollowrow laps half-way past each of two consecutive ing disclosure of afew examples of practice acoscillators of the other row. At the ends,top

cording to the invention which I have chosen for and bottom, thehalf-length conductors 2 l' and 30 presentation in this specification.It will be un- 22' are terminated by capacity areas. The disderstoodthat the following description relates tance between these two capacityareas is conprincipally to these particular embodiments of siderablygreater than the half wave length in the invention, and that the scopeof the invenfree space to which each component oscillator tion will beindicated in the appended claims. is tuned. 7 3

Referring to the drawings, Figure 1 is a dia- The principles involved inthe composite osgrammatic elevation of an oscillator and associcillatorof Fig. 1 and the mode of its operation ated circuits adapted for thepractice of my inwill be developed in the discussion which followsvention; Fig. 2 is a diagrammatic elevation of in connection with Figs.2 to 12.

40 a single component tuned oscillator; Fig. 3 is a A single simpleoscillator is shown in Fig. 2, 40 set of diagrams showing wave shapesfor currents a straight length-of conductor wire with a tuning andelectromotive forces in simple oscillators of coil interposed at itsmiddle and an associated various lengths compared to the wavelength forinductively related circuit 24 bywhich alternatwhich they are tunedalike; Fig. 4 is an ening current energy may be fed into the oscillator.

5 larged diagrammatic elevation of a section of Assuming that variouslengths are given to the the oscillator of Fig. l s o i g conduction andoscillator of Fig. 2 but that in each case the tundisplacement currents;Figs. 5 and 6 are diaing coil is adjusted so that the wave length ingrams showing desirable wave shapes for curfree space will be the same,diagrams arefshown rent and electromotive-force in an oscillator; inFig. 3 for the current Wave shapes and the 59 Fig. '7 is a diagramshowing current wave shapes electromotive force wave shapes. in acomponent oscillator whose length is one In each of these diagrams thecontinuous line wave length; Fig. 8 is a corresponding diagram curveshows the current wave shape of maximum for electromotive forces; Fig. 9is a diagram values, and the dotted line shows the electromoshowingcurrent wave shape in a component ostive force wave shape of maximumvalues. But,

cillator whose length is two wave lengths; Fig. of course, the maxima ofone curve do not occur at the same instant of time as for the othercurve, but are 90 apart in phase. The current is at or near zero whenthe electromotive forces are at or near their maximum. The dotted linesmay also be regarded as representing conditions of static charge whenthe current is at or near zero, as well as representing electromotiveforces.

The third part of the diagram of Fig. 3, for an oscillator of lengthequal to a half wave length in free space, shows a simple readilyunderstood current wave form and electromotive force wave form. Makingthe oscillator a little longer, as in the fourth part of the diagram,that is, fiveeighths of a wave length instead of one-half of a wavelength, it is necessary to interpose a substantial amount of tuning coilinductance at the middle point to preserve the same Wave length in freespace. There will be a sharp potential drop across this inductance coilwhich is represented by the part of the dotted line extending at a rightangle to the length of the oscillator.

Starting with the tuned linear oscillator of the first part of Fig. 3,whose effective length is a quarter wave length, and increasing thislength by one-eighth wave length at each step, but keeping the wavelength in space the same by means of the adjustable tuning coil at themiddle of the oscillator, we proceed from left to right through all theparts of Fig. 3, and at the extreme right We have the case of anoscillator whose length is full two wave lengths. In all these parts ofFig. 3 we assume the same maximum terminal difference of potential, thatis, the ordinates at the ends of the dotted line curves, for example at25, are all equal in absolute magnitude.

From the first part of Fig. 3 at a quarter wave length to the third partat one-half wave length, the intensity of the radiation in theequatorial plane of the oscillator will increase very rapidly. Going on,the intensity decreases until it becomes practically nil in the seventhpart of the figure. Going on, it waxes and wanes as before. There is amaximum at each length of the oscillator that is an odd multiple of ahalf wave length and a null value at each length that is equal to aneven number of half wave lengths.

Certain considerations leading to the'present invention will now bementioned with reference to Figs. 16 to 19.

The maximum possible radiative power per unit of length of a straightconductor is given by the expression 401r Zi watts, in which Z is thelength of the conductor, A is the wave length of the radiation in freespace, and i is'the current amplitude throughout the conductor expressedin amperes. We see therefore that for a given current amplitude and wavelength, this maximum possible radiative power per unit of length of theconductor is proportional to the length of the conductor. But thecondition of the foregoing expression is only true, and the maximumpossible radiative power of a given linear oscillator is therefore onlyattainable when the amplitude i of the current is constant throughoutthe length of the conductor.

Furthermore, an. ordinary linear conductor executing oscillations whosewave length x is small compared to twice the length of the linearconductor, has a current amplitude distribution which is far fromuniform throughout the length of the conductor. Under thesecircumstances the current amplitude is distributed along the conductorin loops with intervening nodes as illustrated by the full line curvesof (1) to (l5-) ,'Fig. 3 of the drawings.

Again, the radiation from each ventral segment of current amplitude insuch a relatively long linear oscillator throws off a separate train ofwaves which pursues its own individual course difierent from thatradiated from any other ventral segment of current amplitude in theoscillator. This is illustrated by Figs. 16 and 17. The arrows indicatethe direction of motion of the dilferent trains of radiation from theseveral ventral segment of current amplitude.

It is to be noted that in Fig. 17, where 2:) there is no radiation inthe equatorial plane of the oscillator ab, while in Fig. 16-, where theradiation in the equatorial plane of the oscillator ab is due solely tothe central ventral segment of current amplitude.

Or inar l e a en he than that in h equator a plfi fit W 3? tha uselessas t; s. o te be ba i ea th by the Heaviside layer and causesinterference with the direct rays as well as interfering with thedirective characteristics of directive receivers andradio compasses.

From all this we see that, other things being equal, the maximumpossible useful power of radiation per unit of length of alinear'oscillator, without capacity areas and tuned by a coil at itscentre to the period of the waves, is attained when l= (or more exactlyZ=0.4767\), under which circumstances the tuning inductance is zero andthe current amplitude distribution is that illustrated in Fig. 3, part(3).

The component of this current amplitude which is constant throughout thelength of the conductor is timesthe maximum amplitude i, so that theforegoing expression in watts becomes loom/2e: 76.21%

watts.

For a given maximum current amplitude i and wave length A, any increaseor decrease of the length Z of the oscillator from (approximate)diminishes the power radiated per unit length of the oscillator from thecentral part of the oscillator (which is all the radiation that iscommonly useful in practice). When the length of the oscillator isl= (ormore exactly 0.97 6x) the power radiated from the central part of theoscillator per unit of length of the oscillator is zero. This is case(1) of Fig. 3 and the case of Fig. 17.

When

(or more exactly 1.4'76 the power radiated from the central part of theoscillator per unit of length of the oscillator is again a maximum,which however is slightly smaller than one third that reached. when Thispower radiated from the central part of the oscillator perunit of lengthof the oscillator reaches subsidiary maxima for (approximately), when pis any odd integer and reaches zero minimum for when q is any eveninteger. The fluctuations of the radiation from the central part of theoscillator per unit of length of the oscillator, and for given i and A,as Z is increased from zero to 4). is illustrated in Fig. 18. In view ofthe foregoing condition in respect of the radiative power of linearoscillators, I have undertaken the task to devise means whereby theradiative power per unit of length of linear oscillators for givenmaximum current amplitude and wave length may be made to increasecontinuously with increase of the length of the oscillator, even whenthe length of such oscillator exceeds the critical value (more exactly0.476%) If this radiative power is tobe made proportional to the lengthof the oscillator as illustrated in the right line of Fig. 19, it isclearly necessary to cause the effective current amplitude, for pointsin space outside the oscillator system, to be constant throughout thelength of the oscillator.

It is not possible to make the total current amplitude in thisoscillator constant throughout the oscillator forthis would involveinfinite phase speed. So I employ a compound oscillator in which theoscillations of the individual parts or component oscillators consist ofnodes and loops, but in which, so far as the field of force external tothe compound or resultant oscillator is concerned, the effective currentamplitude in the compound oscillator will be constant throughout itslength.

The curve (2) of Fig. 19 represents the power radiated per unit lengthof conductor from the central portion of an ordinary linear oscillator,and is the same as the curve of Fig. 18 but to a smaller scale ofordinates and a longer scale of abscissas. It is given to illustrate thegain possible to be effected through the use of the compound oscillator.

The waxing and waning described heretofore of the radiation in theequatorial plane of the linear oscillator of Fig. 3 when its length isin-' creased may be identified with the development of standing waves,the length of each such standing wave being approximately a half wavelength in free space. When these standing waves have a node at thecenter point of the oscillator there will be no radiation initsequatorial plane, but when they have a loop at that point theintensity of the radiation is a maximum. At a considerable distance fromthe oscillator represented by part (I) of Fig. 3, assume a certain planesurface of definite area lying transverse to the equatorial plane, andtransverse to the direction of propagation in that plane. Let the poweror the rate of flow of energy across this area be unity. Next let thelength of the oscillator be increased so that the radiation is amaximum, that is, so that the length of the oscillator is a half wavelength or three halves times a wave length,-or any odd number of halfwave lengths. Then it can readily be shown that the power or energy fiowthrough that same area will be 6.8 units.

The effective length of a linear oscillator for short wave lengths, thatis, its length for the purpose of comparison with the wave length infree space, is very nearly the same as the physical length; the twolengths are connected by the equation Z=l+ \/41.5, where l is theefiective length, l is the physical length and A is the wave length.- r

For intensity of radiation it is evident that the oscillator of thethird part of Fig. 3 is no less advantageous than the longer oscillatorsin the parts of the figure to the right. But if we could haveanoscillator of the same length as the oscillator in the extremeright-hand part of this figure, and have the same electromotive forcesat its ends (as at with the electromotive force distribution as shown bythe dotted line in Fig. 5, and with the current wave shape shown in Fig.5, then we would get far greater intensity of radiation, indeed, theintensity would be sixteen times greater than for the third and eleventhparts of Fig. 3, or somewhat more than. I08 when the intensity for thefirst part of Fig. 3 is taken as the unit. Further, if we were to putcapacity areas at the ends of this oscillator, as shown in Fig. 6, andhave the same extreme electromotive forces at the ends (as at 25"), thenwe might have a current of nearly the same magnitude all along thelength of the oscillator, as shown by the full line curve 5| in Fig. 6,and in this case, if the maximum amplitude of the current were the sameas in Fig. 5, the intensity of radiation would be about 26 times that ofthe third and eleventh parts of Fig. 3, or about 170 times the intensityin the first part of Fig. 3.

The oscillator of Fig. 1 is constructed and de- Theoscillator of Fig. lis built up of 1 equal linear oscillators end to end staggered along twoparallel axes, as already described in connection with: that figure.Thus, when executing free oscillations the two lines of oscillators havethe opportunity to form two sets of loops of potential and currentamplitude which neutralize the effects of each other in the mediumdirectly surrounding the oscillator, leaving only a component of currentwhose amplitude is substantially constant throughout the length of thecomposite oscillator as a whole. This creates an external field ofradiation due to the resultant overall potential amplitude, so thatthere is a substantially constant cylindrical distribution of electricforce around the axis of the oscillator in its intermediate portion.

In Fig. '7 I have shown one component oscillator component oscillator.In the complete, composite oscillator I want a. wave shape such asrepresented by the dotted line 26. But in the complete compositeoscillator there are. two rows. of component oscillators, so I willassume. that only half the desired current represented by the line 26 isto be attributed to the oscillator shown. in Fig. 7. This gives, theline 27. being one component of the current represented by the full linecurve 28., the other component isreadily seen to be represented by thedotted line curve 29,.

As indicated by the dotted line in Fig. 6, the electromotive force isexpected to grade uniformly from one end to the other of the completecomposite oscillator. The actual electromotive force wave shape in asingle component oscillator will be as shown by the fullline curve 30.in Fig. 8, and its, components are readily seen to be given by 31 and32.

The component oscillators of Fig. 1 may have other lengths than a wavelength infree space, as was assumed in connection with Figs. '7 and 8.Figs. 9 and 10 are corresponding diagrams for the case in which eachcomponent oscillator hasa length equal to two wave lengths in freespace.

Whereas Fig, '7 deals with a single component oscillator, Fig. 11 showsa plurality of such oscillators in a short section of length of thecomplete oscillator of Fig. 1. For the sake of clearness, theoscillators have been thrown outof alignment, as indicated by thehorizontal dotted lines each with an arrow head showing the direction ofdisplacement. With the explanationv that has been given heretofore, thesignificance of Fig. 11 will be apparent at once.

Similarly, Fig. 12 shows the electromotive forces for several associatedoscillators as compared with Fig. 8, which is for a single componentoscillator alone.

In Fig. 11 the total current in the complete composite oscillator isrepresented in twoparts, half in the line 33 and half in lines 34 and39, and. in Fig. 12 the electromotive force is represented by lines ofequal slope as at 42 and- 43.

Referring to Fig, 11, consider that. part of the complete oscillatorlying between the points a2 and b1. It will be seen that the alternatingcomponents represented by the dotted curves 31: and 38 tend toneutralize each other for-points outside the immediate vicinity of thetwo-conductorswithin this stretch, and the same is true for'thealternating components of the current amplitudes of the correspondingparts of all juxtaposed component oscillators. But the straightlinecomponents 33 and 39 add to give a straight. line resultantcorresponding to the straightline |v of Fig. 6. Also, in Fig. 12 we seethat the components represented by the curves 4D and 41 neutralize andthe components represented by 42 and 43, coincide to give us the overalldistribution ofelectromotive force.

The two simple oscillators 21 and 22 of Fig. 1 are represented by thelike reference numerals in Fig. 4. Here the dotted lines represent linesof. current flow. Within each unit oscillator 21. or 22 the current flowis conductive, as for example at 20. But in the air gapbetweenthe'members 2| and 22 the current isa displacement current, asrepresented at H? in Fig. 4. Thus, although the conduction current inany one'cscillator unit such as 2| or 22 is anoscillatory-currententirely within that unit, the combined; conductioncurrents and. displacement currents of, the; complete oscillator as awhole give a uniform currentalong the. length of the completeoscillatorasa-whole,

thouglrof course this current ,varies cyclically in time.

Instead of lapping the simple oscillators past each other in the mannerindicated in Fig. 1, they may be built as shown in Fig. 13, where thelower part of each simple oscillator is a cylinder 44 closed above andopen below, and the upper part,

the arrangement of Fig. I may be looked upon as I diagrammatic andequivalent to the arrangement shown in. Fig. 15. The more essentialfeature is thatin a linear sequence of linear oscillators each extendinglengthwise along the general direction of the sequence as a whole, eachoscillator laps a substantial distance,'preferably half-way, past thetwo adjacent oscillators in the sequence.

The elementary theory of the steady state of the. forced current andpotential oscillations in a compound linear conductor of the type thathas been disclosed in Figs. 1, 13; 14 and 15, may be made to rest on thefollowing assumptions, for the sake of simplicity. It may be assumedthat the dissipative resistance of each component oscillator isconcentrated at themiddle point of its length,.that the componentoscillators are all equal, that the oscillations are maintained by equalimpressed, electromotive forces at the middle point of each oscillator,and that the radiation, resistance of the complete compound oscillatormay be assigned in equal portions to the various component oscillatorsand form part of the dissipative resistance that is assumed to be lumpedat the middle points of the component oscillators. e

On the foregoing assumptions which are obv1- ously. valid for the sakeof simplifying the mathematics, the mathematical theory of thedistribution of currents and electromotive forces can be worked out andthe-results afford a check on the theory and may be relied upon to someextent for guidance in constructing and operating the system such asshown in Fig. 1.

The complete compound oscillator acts in one aspect like a balancedmetallic circuit, and in another aspect like a single conductor. In thefirst aspect of a balanced metallic circuit, the cur-rentand potentialamplitudes in this circuit are indicated by the'dotted curves such as 31and 38. 111 Fig. 11 and land 4| in Fig. 12. In the other aspect of asingle conductor, the current amplitude, is indicated by adding theordinatesof the" dotted lines 33and 39 in Fig. 11; and the potentialamplitude is given by a line having double the steepness of the-lines 42and 43 in Fig. 12. J v

The quantity of energy thatcan be radiated at a certain short wavelength from a single oscillator alone is small. Though they quantity ofenergy might be increased by increasing the size of the oscillator andmaking the wave length longer, this may not be what is desired. When itis desired. to make the oscillator larger and thereby increase the;radiated. energy but keep ashort wave length, thenmy system asillustrated diagrammatically in Fig. 1 may be employed. This acts like along oscillator in respect to quantity of energy radiated but keeps theshort wave length established in connection, with each componentoscillator.

What is claimed is:

1. In combination, a series of equal linear oscillators arrangedlengthwise and consecutively along a common line, each oscillator beingtuned to the same comparatively short wave length, each oscillatorlapping half-way past both consecutively adjacent oscilators in series,capacity areas connected to the end oscillators oi the series,respective energy transmitting circuits connected with the oscillators,and phase adjusters in said circuits to keep said oscillators inthe samephase.

2. A radiator for electromagnetic waves consisting of a. series oflinear oscillators each lapping substantially half way on theconsecutively adjacent oscillators of the series, each oscillator havinga winding at its middle point, an inductively related energytransmitting winding at each such place, respective circuits comprisingthese last mentioned windings, a central device to which all thesecircuits are connected, and phase adjusting means in these respectivecircuits.

7 3. A radiator for electromagnetic waves consisting of a series oflinear oscillators each lapping substantially half way on theconsecutively 5 adjacent oscillators of the series, the end oscillatorsof the series have capacity areas, eachoscillatorhaving a winding at itsmiddle point, an inductively related energy transmitting winding at eachsuch place, respective circuits comprising 10 lators lying in staggeredrelation in two rows side 20' V by side, and impedances between theconsecutively adjacent ends of' the oscillators in each row to separatethem electrically. 7 JOHN STONE STONE.

